Voodoo Main Discussion

[dgm]

Hi Good morning Mr. George, the first time I removed the R48 resistance, the MD had an acceptable auduio, after several tests it lowered becoming barely noticeable. Could it have any meaning? And still the cip still has the firmware 1.0 loaded by Endy, could it have some responsibility? Thanks and sorry again for my questions.

[Qiaozhi]

Hi Good morning Mr. George, the first time I removed the R48 resistance, the MD had an acceptable auduio, after several tests it lowered becoming barely noticeable. Could it have any meaning? And still the cip still has the firmware 1.0 loaded by Endy, could it have some responsibility? Thanks and sorry again for my questions.

The only way you're going to trace the cause of this problem is by employing logical fault finding. Trying to guess where the fault is invariably doesn't work. Version 1.0 of the software has nothing to do with the loading issue on the +5V line.

[dgm]

Mr. George, I removed all the integrated from the pcb, I tried to connect the power supply, Tp15 read +05, then except I reinserted one at a time up to the U10 Tl072, inserting this integrated the +05 on the TP15 disappears. I checked the power supplies between 0V -5 on pin 4, and +5 on pin 8, they are correct. What do you advise me to do?
I meant that the TL072 chip works by changing it with a new same result.

[Qiaozhi]

Mr. George, I removed all the integrated from the pcb, I tried to connect the power supply, Tp15 read +05, then except I reinserted one at a time up to the U10 Tl072, inserting this integrated the +05 on the TP15 disappears. I checked the power supplies between 0V -5 on pin 4, and +5 on pin 8, they are correct. What do you advise me to do?
I meant that the TL072 chip works by changing it with a new same result.

The next step would be to measure the current consumption on the +5V line. Disconnect the output pin of U7 (78L05) and insert a current meter in the line. U7 should be capable of supplying 100mA before dropping out. If it cannot manage that value then the 78L05 is either fake or a sub-standard part.

[green]

Measuring resistance from ground to IC pins and other points on the circuit card looking for a low resistance can sometime find the fault.

[Carl-NC]

I would suspect a short circuit between pins 7 & 8.

[waltr]

Never mind... I though I had issues with the LT1054.

Looked at my notes and see it was the +5V regulator, U7 that did not power output with more than a few chips installed.
A 1k Ohm resistor across U7's input to output fixed this.

[dgm]

Hi Good evening everyone, I will make a summary of the problems I had with this Voodoo Project, I assembled and tested the various stages of the circuit with positive results, and once all the components were mounted, and connected a temporary coil for the PI circuit, all it worked with acceptable audio, at one point the audio dropped barely noticeable, and I started having problems with the lack of +5 volts at the Tp15. Replaced the components of the power supply stage, nothing changed. Today I connected a 1k resistor between the input and output of the 78l05, the voltage +5 is back on the Tp15, but after a few seconds the LT1054 pulled out the famous magic smoke. Without the +5 volts I hear very low only the hum of the 555, instead with +5 the circuit works with barely perceptible audio. My question is where can I look for the faulty component in the audio zone. A thousand thanks.

[Qiaozhi]

Hi Good evening everyone, I will make a summary of the problems I had with this Voodoo Project, I assembled and tested the various stages of the circuit with positive results, and once all the components were mounted, and connected a temporary coil for the PI circuit, all it worked with acceptable audio, at one point the audio dropped barely noticeable, and I started having problems with the lack of +5 volts at the Tp15. Replaced the components of the power supply stage, nothing changed. Today I connected a 1k resistor between the input and output of the 78l05, the voltage +5 is back on the Tp15, but after a few seconds the LT1054 pulled out the famous magic smoke. Without the +5 volts I hear very low only the hum of the 555, instead with +5 the circuit works with barely perceptible audio. My question is where can I look for the faulty component in the audio zone. A thousand thanks.

Did you measure the current being drawn from U7, as I asked in post #1534?
Adding a 1k resistor between the input and output of U7 was a bad idea.

[dgm]

Good morning Mr. George, after your post that has mesionated I tested one by one the 78l05 in my possession outside the Voodoo circuit, to limit damage to the pcb, they were genuine, with a resistive load up to 100 ma, they maintained the 5 volts.

[Qiaozhi]

Good morning Mr. George, after your post that has mesionated I tested one by one the 78l05 in my possession outside the Voodoo circuit, to limit damage to the pcb, they were genuine, with a resistive load up to 100 ma, they maintained the 5 volts.

Can you test the LT1054 together with a 78L05 outside the circuit, both in free-running mode and with the sync signal from the Arduino? This will prove whether your LT1054 is genuine or not. Also, you need to measure the current draw on the +5V line as I suggested, because there may be something loading the output.

[dgm]

Hi Good morning, I tried to look for the problem that afflicts my Voodoo project, I tested the transistors Q5 and Q6, then I replaced U6 and U7 and the LT1054, I also checked the Q4 Q7 Q8 Q9 Q10 and Q12 all ok. Now the Tp15 +5 volts starts by itself without the aid of resistors, and I also positioned an instrument to measure the absorption between the output pin of 78l05 and the hole on the pcb, first it absorbs about 3 but and after a few seconds, the +5 volts draws 19.66 but it works in PI mode, but I have very low audio.

[dgm]

Hello everyone, I am still firm with the voodoo project, as far as the very low audio is concerned, I searched in vain for the problem but I could not find a solution. Thanks for your suggestion.

[Orbit]

The best pulse detector with 90 percent discrimination as vlf is in my opinion one detector and the only one for now is the new detector from the picture I will set the top side of the pcb..It can work with both mono and dd coils depths indisputably similar to gpx minelab I am sincerely delighted, The tdi-sl that I finished but not in the box is also very good but I am bothered by tc holes this pulse has almost no tc holes at all!

[Qiaozhi]

The best pulse detector with 90 percent discrimination as vlf is in my opinion one detector and the only one for now is the new detector from the picture I will set the top side of the pcb..It can work with both mono and dd coils depths indisputably similar to gpx minelab I am sincerely delighted, The tdi-sl that I finished but not in the box is also very good but I am bothered by tc holes this pulse has almost no tc holes at all![ATTACH]55949[/ATTACH]

The TDI has target holes because it attempts to discriminate using conductivity, whereas Voodoo has not target holes since it provides true ferrous / non-ferrous discrimination.

The Minelab GPX iron reject works differently to all other detectors. When the coil passes over a ferrous target, it momentarily blanks out the threshold but doesn’t go completely silent. It also creates an audio "tail" as you move away from the ferrous target. Apparently it works this way to avoid missing certain gold nuggets that may also get rejected.